OAKLAND -- A crowd of several hundred people protesting the acquittal of George Zimmerman in Florida briefly shut down traffic on Interstate 880 during a lengthy march Monday evening, blocking numerous streets before a group of more than 100 people scuffled with police shortly after 11 p.m.

At least one person was injured when he was struck on the head with a hammer or a similar object. Witnesses said a protester was injured and writhing in pain at Broadway and 16th Street after apparently being struck in the shoulder by a police projectile.

The late-night skirmishes began after police charged at several vandals who smashed windows at the Men's Warehouse at 15th Street and Broadway.

Protesters later marched up Broadway and Telegraph Avenue, where people stood in front of bars and restaurants to protect them from window-smashing vandals.

A waiter was hit with what appeared to be a hammer while protecting the windows at Flora, a restaurant at the corner of Telegraph and 19th Street.

"Protesters with black masks approached the window and tried to bang at it," said bartender Phillip Ricafort. "(The waiter) said, 'Don't do that!' and the guy turned around and smacked him in the face with a hammer" or another metal object.

"It was gruesome," said Ricafort. He said his co-worker was bleeding from the face.

Vandals also targeted Flora's windows over the weekend; several windows were still boarded up.

The man's co-workers were helping him ice his head on a chair in the back of the restaurant as they waited for an ambulance. Police also stopped to check on them before marching on.

The evening began peacefully, though police were soon challenged as protesters shifted directions in an attempt to stay ahead of the officers keeping tabs on them.

Protesters chanted "Trayvon" as they marched through downtown Oakland and then around Lake Merritt. Several protesters wearing masks tagged buildings as they marched. An American flag was burned at the intersection of Lakeshore and El Embarcadero near the eastern tip of Lake Merritt.

The cat-and-mouse game between protesters and police extended to Twitter, where protest sympathizers listening to the police scanner reported police directives for marchers to read.

A mutual aid call from Oakland brought law enforcement officers from at least nine other departments, including the California Highway Patrol, the Alameda County Sheriff's Office and police departments in Berkeley, San Leandro, Hayward, Pleasanton, Union City, Fremont and Newark.

Officials said they had arrested nine people, including one juvenile, on misdemeanor and felony charges ranging from assault with a deadly weapon to vandalism.

Of the nine suspects arrested, three were Oakland residents, according to Oakland police Officer Johnna Watson.

The protesters gathered around 6 p.m., rallying in Frank Ogawa Plaza before moving south and walking up onramps to Interstate 880 at Broadway around 7:15 p.m. Police quickly swarmed the onramp, herding protesters off the roadway and arresting at least one person before reopening all lanes around 7:30 p.m.

Several demonstrators linked arms in front of motorists, while others chanted "If LA can do it, we can do it too." One officer shouted at them, "You've got to go. You will go to jail."

The protest then moved through Chinatown, heading around the lake's west shore. Protesters were headed off by police as they attempted to walk onto Interstate 580 at Lakeshore Avenue shortly before 9 p.m.

About 250 demonstrators were still on the march around 10 p.m. when the group encountered police outside the Rene C. Davidson Courthouse. The group headed back toward downtown, where lines of riot gear-clad police attempted to cut them off as officials read dispersal orders over loudspeakers.

Protests also were reported in Los Angeles on Monday as the nation continued to deal with the acquittal of Zimmerman, a neighborhood watch volunteer who shot and killed Trayvon Martin, an unarmed African-American teenager who was returning home from a trip to the grocery store.

The case prompted a national debate over racial profiling and the Saturday's verdict by a Sanford, Fla. jury prompted mostly peaceful weekend protests in San Jose, Los Angeles, and San Francisco.

In Oakland, however -- a city that has become accustomed to raucous demonstrations since Oscar Grant was shot and killed by a BART police officer four years ago -- nightfall led to rowdy, chaotic protests that, in a few instances, turned violent.

A loosely organized protest of about 150 people late Saturday night resulted in widespread vandalism, and a few protesters beat one man in a Broadway doorway near Frank H. Ogawa Plaza until other protesters ended the skirmish. The man was helped to his feet and did not appear seriously injured.

The group shattered numerous storefront windows, spray-painted buildings and a police car, and started several small fires in the streets. No arrests were reported.

Sunday's demonstration began peacefully with a two-hour afternoon march from downtown to West Oakland and back, ending with protesters sitting in the intersection of 14th Street and Broadway.

Hours later, a small group of protesters started heading north on Telegraph Avenue and quickly turned violent, attacking a KTVU photographer and a Bay Area News Group photographer who suffered minor injuries when he was kicked on the ground and his camera was ripped from his shoulder. Police made only one arrest, of someone who refused to disperse and did not have identification.

Businesses along Telegraph Avenue and Broadway took the brunt of the damage from the weekend protests, with 61 windows broken or shattered at 14 buildings, according to police.